Legacy of Kain. Ever since Amy Hennig left for Naughty Dog I lost most, if not all, hope for a new one. Even though she did leave for a better company, and it gets me excited for future Naughty Dog titles, I still feel a small bit of sorrow for Crystal D.

Shadow Hearts. Pretty self explanatory. I loved the series and would love another entry but that's never going to happen.

Breath of Fire, Lunar, Golden Sun, Arc the Lad. I know of a few more series, but they most likely will get another entry in the coming years.

Actually, I'm going to take the original poster and topic title a bit more literally here. Perhaps this is what's really meant since missing a game does not inherently mean you want a sequel.

Phantasy Star is probably the only one I can really think of, the series had generally been good for the time of each installment and IV has aged well, but it ended well and I doubt Sega could recapture the magic anyway. Quintet games are something I miss too, I'd like it if they could get together and make a new game on the DS or something, but that's unlikely and I'm not sure can be even be done nowadays.

Dude, Star Ocean? Star Ocean is FAR from being a dead series. It's alive and kicking really well, we've gotten installments pretty regularly, Star Ocean 4's long since been announced for the 360, and US gamers will soon get the Star Ocean 1 and 2 PSP remakes.

And Fallout? Dead? I'd have thought that years ago, but Fallout 3's coming out this year and it's so far blown everyone away at E3. Fallout's not dead.

And Mario? Zelda? I think you've just missed the boat on this topic. If Mario and Zelda are dead series, then I'm a monkey's uncle.

Now Alex Kidd on the other hand, THERE'S a dead series I'd like to see another installment of.